Multiple tap resistance unit and the method of making the same



Jan. 27, 1953 UNLOP 2,627,008

J; 'D MULTIPLE TAP RESISTANCE UNIT AND THE METHOD OF MAKING THE SAMEFiled June 25, 1951 1FIG.I

F'IG.3

INVENTOR. JAM ES DU N LO P ATTORN EY.

Patented Jan. 27, 1953 UNI TED STATES PAT ENT OFFICE '-=2,s27,00sMcn'iIPLEflrARnEs N E ii i-T ND METHOD OF MAKING THE SAME James Dunlap,Philadelp'hia,-Pa. "Application June 25, 1951, 'Seria I No. assesclaims.

This invention relates to rnultiple" tap resistance' units, and the'rnethod of making the'sa'me, which unitsare used, in various electricalinstruments and apparatus, to provide resistance which may be variedstep by stepin the use of the devices of which such resistance unitsform a part.

The principal objector the present invention is to provide a multipletap resistance unit which will be simple in construction, relativelyinexpensive to manufacture, and which will be durable in use so thatthere will be littlelikelihood of damage to the delicate parts eventhough'said units may be more or less roughly used.

The nature and characteristic features of the invention will be morereadily understood from the following description, taken in connectionwith the'accompanying drawing forming-part hereof, in which: 7 v

Figure 1 is a side elevation, somewhat enlarged, of a resistance unitembodying the main features of the present invention, the same beingshown in an intermediate stage of its construction;

Fig. 2 is a transverse section taken approximatelyon' the "line 2-2 ofFig. 1, still further enlarged;

Fig. 3 is a sectional viewillustrating a form of the invention in whichthe resistance coils are of a non-inductive character; and

Fig. 4 is a view illustrating a, resistance unit embodying the mainfeatures of the present invention shaped for mounting in a particularform of electrical device.

It should, of course, be understood that the description and drawingherein are illustrative merely, and that various modifications andchanges may be made in the structure and method disclosed withoutdeparting from the spirit of the invention.

The invention will be best understood by first referring to the methodof making a typical unit embodying said invention. A strip H) ofinsulating material of the proper characteristics is employed in themaking of the unit. Various materials will be found adaptable for thispurpose, but the preferred material consists of nylon in strip form, thestrip being of the requisite width and thickness.

At spaced intervals along the strip, circular discs of the material arepunched out, which leaves the strip ID with a series of spaced holes II.The punchings, that is the discs which are cut out of the strip, arethen machined into the form of miniature spools I2, shown incross-section in Fig. 2 of the drawing, upon which the resistance wire13 is wound.

'2 'wnenfuoweven the resistance coils 'musttbe of anon-inductivecharacter, then the spools l2 -shown in'Fig.'3 of the drawing maybeused, each providing two annular compartments, in one of whichthewinding I4 is reversed indirection-with respecttothe other winding 15.

After the miniature spools [2 have been'woiind, the same are replaced inthe openings H which were left in thestrips '10 "when. the discs, fromwhich'"the spools l2 were "madefwera'pu'nched from the strip.

The tap"wires l6 extend 'transve'rsely with respect to the strip 10.Each ofsaid wires 1 8 passes from one face of the strip [0 to theotherthrough a ertures 11 provided for that purpose, and one end' [8 ofeach tap wire is b'entaroundthe lower margin of the strip.Theoth'er'end'of'each'wire "in the strip [0, the'lead-inwires 20 for theseveral coils which are mounted on the spools i2 are connected thereto,preferably by soldering. The strip ID, with the spools and wires mountedtherein as aforesaid, is then coated by dipping or spraying. The coating25 preferably being of a suitable synthetic resinous material which willserve to encase the strip and the spools mounted therein in a protectivecoating. This coating will also serve to seal the various crevices,interstices, and openings against the entrance of moisture or otherdeleterious materials, whether the same be of a gaseous, liquid, or dustlike character.

After the strip with the spools mounted therein has been coated asaforesaid, the strip may then be bent to any desired shape, as forexample, in the circular form as shown in Fig. 4 of the drawing. Whenthe strip is thus bent the spools upon which the resistance wire iswound will be held in place in the strip by the coating 25, and will beconstrained to follow the curvature when the strip is so shaped.

By the foregoing arrangement there is provided a simple, convenient, andrelatively inexpensive form of resistance unit, which has been found tobe quite practical and exceedingly useful in various applications inelectrical devices, instruments and apparatus.

I claim:

1. A multiple tap resistance unit comprising a strip of insulatingmaterial having a plurality of spaced holes, spools mounted within andfilling said holes, said spools being made of the same material as thestrip, and resistance wire wound on said spools.

2. A multiple tap resistance unit comprising a strip of insulatingmaterial having a plurality of spaced holes, spools mounted within andfilling said holes, said spools being made of the same material as thestrip, resistance wire wound on said spools, and a protective coating onthe assembled structure.

3. A multiple tap resistance unit comprising a strip of insulatingmaterial having a plurality of spaced holes, spools mounted in andfilling said holes made of the same material as the strip, resistancewire wound on said spools, the tap .wires to which lead-in wires of thespool Windings are connected secured to the strip and extendingtherefrom at places between the spools.

4. A multiple tap resistance unit comprising a strip of insulatingmaterial having a plurality of spaced holes, spools mounted in andfilling said holes made of the same material as the strip, resistancewire wound on said spools, the flange portions of said spools beingnotched for the passage therethrough of lead-in wires extending to thewindings on said spools, tap wires to which said lead-in wires areconnected secured to the strip and extending therefrom at places betweenthe spools.

5. A multiple tap resistance unit comprising a strip of insulatingmaterial having a plurality of spaced holes, spools mounted in andfilling said holes made of the same material as the strip, resistancewire wound on said spools, the flange portions of said spools beingnotched for the passage therethrough of lead-in wires extending to thewindings on said spools, tap wires to which said lead-in wires areconnected secured to the strip and extending therefrom at places betweenthe spools, and a protective coating on the assembled structure.

6. The method of making a multiple tap resistance unit which consists incutting a series of spaced holes in a piece of insulating material,

4 making spools to fit Within said holes, winding resistance wire onsaid spools, and then placing the spools within the holes to fill thesame.

7. The method of making a multiple tap resistance unit which consists incutting a series of spaced holes in a piece of insulating material,making spools to fit within said holes, winding resistance wire on saidspools, then placing the spools within the holes to fill the same, andcoating the assembled structure with a layer of protective and sealingmaterial.

8. The method of making a, multiple tap resistance unit which consistsin punching a series of spaced holes in a strip of insulating material,utilizing the punchings from the strip to make spools, windingresistance wire on said spools, then replacing the spools in the holesin the strip, mounting a series of tap wires on the strip at placesbetween the spools, and connecting the spool windings to the tap wires.

9. The method of making a multiple tap resistance unit which consists inpunching a series of spaced holes in a strip of insulating material,

utilizing the punchings from the strip tomake spools, winding resistancewire on said spools, then replacing the spools in the holes in thestrip, and coating the assembled structure with a layer of protectiveand sealing material.

10. The method of making a multiple tap resistance unit which consistsin punching a series of spaced holes in a strip of insulating material,utilizing the punchings from the strip to-make spools, windingresistance wire on said spools, then replacing the spools in the holesin the strip, mounting a series of tap wires on the strip at placesbetween the spools, connecting the spool windings to the tap wires, andcoating the assembled structure with a layer of protective and sealingmaterial.

JAMES DUNLOP.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Name Date

